Java JFrame中的滚动条未显示

我试图在我的JFrame中添加一个水平滚动条，它实际上包含一组JButton。在我的代码中，您可以看到我添加了19个名为Ground的绿色jbutton，以及其他几个按钮。最后几部电影显然已脱离了银幕。我想要的是实现一个滚动条，这样我就可以查看所有的按钮。不幸的是，我似乎无法让JScrollPane滚动条工作。它会显示，但实际上不会滚动

我希望得到一些反馈

import javax.swing.*;
import java.awt.*;
import java.util.ArrayList;

public class World {
    public static void main(String[] args) {
        // Just defining my own colour hues
        Color blue = new Color(77, 121, 255);
        Color green = new Color(0, 255, 0);
        Color grey = new Color(166, 166, 166);
        Color red = new Color(255, 102, 102);

        // Create the JFrame
        JFrame f = new JFrame("World");

        // Creating the JButtons. They're added to the JFrame at the end of the code.
        JButton object0 = new JButton("Object");
        object0.setBounds(0, 0, 80, 80);
        object0.setBackground(red);

        JButton object1 = new JButton("Object");
        object1.setBounds(80, 80, 80, 80);
        object1.setBackground(red);     

        // This just automatically adds the "Ground" buttons to the frame, as they are many of them.
        ArrayList<JButton> groundList = new ArrayList<JButton>();
        for (int i = 0; i < 19; i++) {
            groundList.add(new JButton("Ground"));
        }
        JButton temp;
        int x = 80;
        for (int i = 0; i < 19; i++) {
            temp = groundList.get(i);
            temp.setBounds(x, 0, 80, 80);
            temp.setBackground(green);
            f.add(temp);
            x = x + 80;
        }

        JButton wall = new JButton("Wall");
        wall.setBounds(80, 160, 80, 80);
        wall.setBackground(grey);

        JButton avatar = new JButton("Avatar");
        avatar.setBounds(0, 80, 80, 80);
        avatar.setBackground(blue);

        f.add(object0);
        f.add(object1);
        f.add(wall);
        f.add(avatar);      

        JScrollPane scroll = new JScrollPane(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
        scroll.setVisible(true);
        f.add(scroll);  // This adds the scroll bars but doesn't actually make them work.   
        f.setSize(800, 200);
        f.setVisible(true);     
    }
}

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这是因为您需要将可滚动内容放到滚动条实例中。 因此，首先需要创建一个JPanel并将所有按钮添加到面板中，然后创建JScrollPane，并将面板传递给其构造函数

将UI组件直接添加到JFrame不是一个好的做法

尝试运行此程序并检查更改，它应该可以工作：

import javax.swing.*;
import java.awt.*;
import java.util.ArrayList;

public class World {
    public static void main(String[] args) {
        // Just defining my own colour hues
        Color blue = new Color(77, 121, 255);
        Color green = new Color(0, 255, 0);
        Color grey = new Color(166, 166, 166);
        Color red = new Color(255, 102, 102);

        // Create the JFrame
        JFrame f = new JFrame("World");
        //button will be added to this panel
        JPanel myPanel = new JPanel();

        // Creating the JButtons. They're added to the JFrame at the end of the code.
        JButton object0 = new JButton("Object");
        object0.setBounds(0, 0, 80, 80);
        object0.setBackground(red);

        JButton object1 = new JButton("Object");
        object1.setBounds(80, 80, 80, 80);
        object1.setBackground(red);     

        // This just automatically adds the "Ground" buttons to the frame, as they are many of them.
        ArrayList<JButton> groundList = new ArrayList<JButton>();
        for (int i = 0; i < 19; i++) {
            groundList.add(new JButton("Ground"));
        }
        JButton temp;
        int x = 80;
        for (int i = 0; i < 19; i++) {
            temp = groundList.get(i);
            temp.setBounds(x, 0, 80, 80);
            temp.setBackground(green);
            myPanel.add(temp);
            x = x + 80;
        }

        JButton wall = new JButton("Wall");
        wall.setBounds(80, 160, 80, 80);
        wall.setBackground(grey);

        JButton avatar = new JButton("Avatar");
        avatar.setBounds(0, 80, 80, 80);
        avatar.setBackground(blue);

        myPanel.add(object0);
        myPanel.add(object1);
        myPanel.add(wall);
        myPanel.add(avatar);      

        //notice how the panel is dropped inside the scroll pane
        JScrollPane scroll = new JScrollPane(myPanel, ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
        scroll.setVisible(true);
        //f.add(scroll);  // This adds the scroll bars but doesn't actually make them work. 

        //finally add the scroll to frame's content pane .. which is more proper than adding to frame directly
        f.getContentPane().add(scroll, BorderLayout.CENTER);
        f.setSize(800, 200);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
        f.setVisible(true);     
    }
}

结果:

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JScrollPane是一个复杂的组件，您确实应该从阅读和开始，更好地了解它的工作原理和使用方法。JScrollPane包含一个JViewportView，它维护对要考虑用于布局的基本组件的引用，在此基础上，添加组件，然后让布局管理器系统执行其余操作。。。这意味着，你不会逃脱挫折，你必须努力了解布局管理器是如何工作的。我根据你的实现添加了代码示例，水平滚动按预期工作。回答很好，@Cortex；非常感谢你。一个简单的问题是：如果我想按按钮的顺序准确地放置按钮，这就是为什么我在按钮上使用了setBounds方法，我该如何保持原来的布局，或者更确切地说，保持原来的顺序，并且仍然有滚动条？很高兴我帮了忙，在这种情况下，由于FlowLayout，收进边界的x和y将无效。按钮将按添加到面板的顺序显示。因此，请更改myPanel.add.；的位置/顺序。。；。还要添加这个temp.setTextInteger.toStringi；在循环的绿色按钮中，您可以看到加法的顺序。一般来说，课程安排包含在主题下，我鼓励你花时间学习。

myPanel.setPreferredSize(new Dimension(100, 200));